Standby Database



----- Check whether the --archive log is corrupted or not    

    alter system dump logfile '<full path/archive log file name>' validate;

On your physical standby database:
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    SQL> SELECT * FROM V$ARCHIVE_GAP;

----- command for switchover:-

    ALTER DATABASE RECOVER MANAGED STANDBY DATABASE THROUGH ALL SWITCHOVER DISCONNECT  USING CURRENT LOGFILE
----- command for putting database in real time apply:-
    ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE;
----- command for putting database in MRP :-
        alter database recover managed standby database disconnect from session;
----- Command for cancelling  MRP :-
    ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;
----  Command to use Active Data Guard  (db is in MRP & open in read only for querying) :-

    ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;
    SHUTDOWN IMMEDIATE;
    STARTUP MOUNT;
    ALTER DATABASE OPEN READ ONLY;
    ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION;